The advent of virtualization technologies for computing resources has provided benefits with respect to managing large-scale computing resources for many users with diverse needs and has allowed various computing resources to be efficiently and securely shared by multiple users. For example, virtualization technologies may allow a single physical computing machine to be shared among multiple users by providing each user with one or more virtual machines hosted by the single physical computing machine using a hypervisor. Each virtual machine may be a guest machine acting as a distinct logical computing system that provides a user with the perception that the user is the sole operator and administrator of a given virtualized hardware computing resource. Furthermore, some virtualization technologies are capable of providing virtual resources that span two or more physical resources, such as a single virtual machine with multiple virtual processors that spans multiple separate physical computing systems.
In many environments, operators of provider networks that implement virtualized computing, storage, networking, application and/or other network-accessible functionality may allow users to a bid on unused virtualized resources at a specific point in time. For example, a user may place a bid on an interruptible computing instance (e.g., current unused computing capacity). At a time that the bid placed by the user exceeds a price for the interruptible computing instance, the user's bid may be accepted and the user may have access to the interruptible computing instance until such a time that the price moves above the bid price and the interruptible computing instance is reclaimed. Interruptible computing instances may provide a user with the ability to bid on a number of specific types and configurations of computing instances for a short term. This may allow the user to avoid costs related to long term commitments for a computing instance and reduce computing costs when available computing resources are available.